Curable compositions containing an encapsulated reaction component have been suggested in the art. U.S. Pat. No. 4,200,480 relates to an adhesive composition comprising a solution of non-reactive elastomer as for example, butadieneacrylonitrile rubber dissolved in a mixture of polymerizable acrylic monomers and acrylic acid monomer such as methyl methacrylate and acrylic acid, containing a polymerization catalyst such as benzoyl peroxide, and applying to the other mating surface a tertiary amine activator encapsulated in a rupturable microsphere and dispersed in the adhesive composition. The microspheres may be ruptured before or after the adhesive is applied through a physical crushing or shearing force.
Additionally, U.S. Patent Application Publication No. 2004/0014860 describes a reaction adhesive comprising a reactive resin, and encapsulated curing agent for the resin and crystalline monoparticles with ferromagnetic, ferrimagnetic, superparamagnetic, piezoelectric or ferroelectric properties. The reaction adhesive is applied to the substrates and the substrates joined. The adhesive is subjected to an alternating electrical, magnetic or electromagnetic field to release the curing agent by heating the nanoparticles and causing the microcapsule shell to melt, swell or rupture.
This method, however, relies on a thermal interaction to cause the release of cure agent. There are applications which are temperature sensitive in which the adhesive must be maintained at or below a specific temperature, or where heat generated within the adhesive could damage components of the adhesive or the substrates being bonded.
It would therefore be desirable to provide an adhesive containing an encapsulated cure agent which can be activated at a desired time without physically shearing the material or internally heating the material.